1. Field of the Invention
The invention relates to a local area network (LAN) system for communicating control signals and other information in a small watercraft having an outboard motor.
2. Description of the Related Art
Watercraft (e.g., personal watercraft or boats) typically incorporate internal combustion engines along with propulsion units to provide power and propel the watercraft in a variety of popular applications. The internal combustion engines and propulsion units are outboard motors on many watercraft. In a conventional watercraft, cables, wires, and hoses are used to manage and operate the watercraft and the outboard motor. The number of cables, wires and hoses needed to interconnect the hull and the outboard motor often introduce complications and delays when mounting the outboard motor to the hull.
For example, cables and wires are conventionally used to control a throttle that regulates the opening of an engine throttle valve of the outboard motor, to control a shift device that switches a transmission to provide forward, reverse and neutral operational modes of a propulsion unit of the outboard motor, and to control a steering mechanism that translates a driver's steering requests into directional movements of the propulsion unit. Hoses supply fuel from a fuel tank to the outboard motor and supply oil from an oil tank to the outboard motor. A wiring harness enables communication between the outboard motor and the hull. For example, navigational information, engine parameters and watercraft parameters are communicated via the wiring harness to a display to be viewed by the operator. A battery cable supplies electrical energy from a battery disposed in the hull to the outboard motor.
An arrangement utilizing electrically controlled throttle and transmission activation was proposed in the Japanese Patent JP 3065369. A remote control unit is disposed proximate to the operator's seat in the hull to enable the operator to perform the shifting and throttling operations via electrical signals communicated from the remote control unit. The electrical signals are communicated to electric motors mounted in the hull that operate actuators and other devices. The actuators and other devices in the hull move wires in response to the operation of various levers of the electronic remote control unit by the operator to cause the shifting and throttling operations. Thus, the outboard motor is controlled according to the movement of the control levers without requiring direct mechanical interconnections from the control levers to the outboard motors. Yet, wires are used to transmit forces mechanically from the actuators and other devices mounted in the hull to the outboard motor to control the engine throttle, transmission shifting, and steering. The actuator wires must be connected between the actuators and the outboard motor when the outboard motor is installed on the hull of the watercraft.
Recently, local area network (LAN) systems and developing information technology have been used in watercraft to interconnect the hull and the outboard motor. Known LAN systems communicate with the outboard motor and the watercraft to receive parameters representing the operation of the outboard motor and the watercraft. Information responsive to the parameters are displayed to the watercraft operator. Although such LAN systems reduce the number of wire harnesses in the watercraft, conventional LAN techniques are used only to communicate watercraft and outboard motor parameters to the operator's display, and the LAN systems are not used to communicate control information from the remote throttle and shifting control unit and from the steering device to actuate the motors that operate the throttle, shifting, and steering mechanisms. Therefore, the number of wires used to control a drive-by-wire system in known watercraft has not been significantly reduced.